The participants in this proposal require an XL-I analytical ultracentrifuge from Beckman Coulter together with an assortment of necessary accessories, to advance their research projects. The scientists involved are from the Wadsworth Center, Albany Medical College, and Albany College of Pharmacy. Currently there is no analytical ultracentrifuge in this region. The PI has extensive previous experience with the old model F analytical ultracentrifuge, as do two other participants. The instrument will be located at the Wadsworth Center in an existing core facility where the PI is core director. The PI and the associate core director will have the responsibility of becoming expert with this technology and training others in its use and applications. Since it is to be located in an existing core that has several instruments, there is considerable expertise in how to properly provide such a scientific service. A salient reason to acquire the analytical ultracentrifuge is that it will enhance the other existing instrumentation, which includes dynamic light scattering, HPLC, circular dichroism and fluorescence. The projects are mostly NIH funded, and involve research projects that the analytical ultracentrifuge is capable of handling: including the accurate determination of oligomeric states, the self-assembly properties of a protein, the study of complex formation between unlike molecules, and shape changes in molecules. Several of the projects propose to study complex interactions between unlike proteins or proteins and nucleic acids. The analytical ultracentrifuge has a number of instrumentation strategies and various powerful software protocols to solve these biologically important problems. It is a versatile and sometimes singularly appropriate technological approach to biochemical and biophysical progress.